Adaptive Attachment Wheel for Wheelchairs

ABSTRACT

The invention relates to an adaptive attachment wheel for wheelchairs, formed as a unit consisting of: a wheel (5); frame segments (1); adaptation shells (7, 8) for lateral guidance on the wheelchair front tubes; and at least one holding element (6) that can be fastened to the wheelchair; such that, when the adaptive attachment wheel is attached to the wheel-chair, the adaptation shells (7, 8) are brought together with the wheelchair front tubes, the front casters of which are lifted off of the ground, and a three-wheeled wheelchair is produced, the front wheel (5) of which can be steered and braked by means of an one-hand steering system (13).

The invention relates to a detachable adaptive attachment wheel supposed to expand the range of use of the wheelchair otherwise limited greatly. It comprises an unit consisting of an attachment wheel, frame segments and at least one holding element fastened to the wheelchair such that when attaching the adaptive attachment wheel to the wheelchair its front casters are lifted off of the ground and a three-wheeled wheelchair is produced.

Wheelchair attachment wheels with foldable frames are already known, which are fastened by means of mechanical holding elements, and others with rigid frames with which the fastening is achieved by means of a plug connection. In addition, there are wheelchair bicycles capable of being fastened to the wheelchair without any attachment parts, e.g. by means of screwable clamping jaws.

Such embodiments are well known from:

DE 10 2007 014 533 B3,

DE 100 28 338 C2,

DE 101 02 855 C1,

DE 200 07 793 U1,

DE 41 07 410 C2,

EP 0911 010 A2.

According to prior art so far, for wheelchair users it is difficult to attach or transport the usually heavy and big configurations with steering systems and brakes autonomously.

However, smaller configurations solving this handling problem don't have active driving facilities such as e.g. brake and steering system, thereby making driving difficult and unsafe. Furthermore, heavy and space-consuming attachment parts at the wheelchair are often necessary by which its handling is aggravated in daily use.

The invention has the objective to provide an adaptive attachment wheel of the above mentioned type such that the wheelchair user can easily and autonomously attach and furthermore effortlessly transport it. Additionally, driving on poorly conditioned routes is supposed to be facilitated. The drive power ought to remain unchanged by direct, non-retarded steering for being able to cope with laterally inclined pathways with as little effort as possible so that no drive power has to be applied for steering. Thus, the tendency of the wheelchair to align towards downhill is expected to be prevented. During downhill driving much fraction between the hands and the gripping rings is produced with conventional decelerating the wheelchair resulting in a fast temperature rise of the palms and requiring much effort. A calliper brake located at the front wheel solves this problem and is additionally intended to be combinable with the conventional deceleration.

Furthermore, the preconditions for a high-grade adaptability to the needs of the user and to the differently configured types of wheelchair frames are supposed to exist. The holding elements attached to the wheelchair are to be configured in a form as small and light-weighted as possible.

This means that a product is to be formed by this new attachment wheel, the wheelchair user can transport with his car completely autonomously and independently of other persons, can attach it easily and thus can drive on different pathways (for example on trails, grassland, sand, gravel, uphill, down-hill, inclined routes) actively, safely and without any assistance of a steering system and a brake.

These objectives are achieved by the features specified in the claims.

Prior to the attachment of the adaptive attachment wheel to the wheelchair the holding elements are clamped to its wheel-chair front tubes in equal heights. In order to achieve the functional position, the front wheel resting on the ground is firstly inserted into the holding elements with the upper adaptation shells. By means of the tensioning element to be put around the wheelchair front tubes, now the lower adaptation shells of the frame segments are brought together with the wheelchair front tubes by means of a tensioning mechanism wherein the casters of the wheelchair lift off of the ground.

It is advantageous to configure the holding elements as a two-part ring with a groove into which the upper adaptation shells can be inserted and engage to ensure a backlash-free and sustainable connection between the wheelchair and the attachment wheel as well as to facilitate the assembly and the attachment.

Advantageously, the tensioning elements to be put around the wheelchair frame are provided with a soft surface to avoid damages to the wheelchair frame.

Advantageously, the tensioning mechanism for tensioning the tensioning elements is provided with a locking feature preventing an autonomous release of the fastening.

Advantageously, the adaptation shells are configured in a rotatable and swivelling manner to achieve the adaptability to different wheelchair frame types and the parallelism of both vertical joints as a geometrical condition for performing the lifting function by means of a tensioning mechanism.

Advantageously, the inner dimension of the adaptation shells having a soft surface are adaptable to the outer dimension of the wheelchair front tubes.

Advantageously, two frame segments are present which can be swivelled symmetrically horizontally by rotating joints at the steering tube to enable the adaptation to different frame widths and to keep the packing size small.

Advantageously, the frame segment has a telescopically adjustable inner holm with an offset to the end of which an adaptation shell is fastened to enable the adaptation to different frame types.

Advantageously, the contact point of the wheel is positioned behind the intersection point of the extended steering axis and the ground.

Advantageously, the steering system has an adjustable sluggishness as well as an additional mid position to guarantee the tracking stability. This is particularly advantageous with the two-handed propelling of the wheelchair because a tail wag of the front wheel is prevented on poorly conditioned routes.

Advantageously, the handlebar with a brake is designed for the one-hand operation as well as performed adjustable in height and length for physical adaptability.

In the following, the invention is described in more details on the basis of the embodiment shown in the drawings. However, it should here be clarified that it is an exemplary embodiment variations of which are possible within the scope of the claims.

FIG. 1 shows a general view of an exemplary embodiment of the attachment wheel adaptation according to the invention;

FIG. 2 shows a plan view of the attachment wheel adaptation shown in FIG. 1 in packing size;

FIG. 3 shows a plan view of the unit without a handlebar;

FIG. 4 shows a cross-sectional view of a steering tube and a handlebar stem;

FIG. 5 shows an exploded view of the steering tube and the handlebar stem;

FIG. 6 shows a cross-sectional view of an adaptation ring;

FIG. 7 shows a perspective view of the upper adaptation shells with joints;

FIG. 8 shows a perspective view of the lower adaptation shells with joints;

FIG. 9 shows side views of the one-hand handlebar; and

FIG. 10 shows the initial and end/functional position during fastening the attachment wheel adaptation to the wheelchair in a side view.

The embodiment (FIG. 1) consists of one left and one right frame segment (1) fastened to the steering tube (2) by means of joints (3). In connection with the lockable shearing mechanism (17, 18, 19; FIG. 3) a symmetric triangle frame continuously adjustable in width for different widths of wheelchair seats results. In order to guarantee a maximum adaptability each of the upper adaptation shells (7) is connected with the respective frame segment (1) by a horizontal joint (33; FIG. 7), a vertical joint (34) and a rotating joint (35). The adaptation rings (6) are clamped to the wheelchair front tubes (26; FIG. 10) in the upper section at the same height. Further modifications of the wheelchair are not required. The upper adaptation shell (7) comprises a hook (28; FIG. 7) engaging the adaptation ring (6; FIG. 1 and FIG. 6) during inserting the adaptation shell into it such that the attachment wheel is fixed at the wheelchair and hereby facilitating the further adaptation procedure.

The lower adaptation shells (8; FIG. 8) are rotatably connected with the offset tubes (9) which are guided in the lower tube of the frame segment (1) as an inner tube in a telescopically adjustable and rotatable manner and can be locked by a clamping (10). This adjustability enables an adaptation of the attachment frame to wheelchairs with different front tube angles as well as to special variants as, for example, adduction frames.

At each frame segment (1) a tensioning mechanism (11) is located having a tensioning element of textile belt with a loop (12) at the end which is hung up at the frame segment (1). To achieve the functional position (FIG. 10, below), the upper adaptation shells (7) are inserted into the grooves of the adaptation rings (31; FIG. 6), the tensioning elements (12) fastened to the tensioning mechanisms (11) are led around the wheelchair front tubes (26; FIG. 3, 10), hung up at the frame segments (1) and tensioned by means of the tensioning mechanism (11). During this procedure the lower adaptation shells (8) are approaching the wheelchair front tubes (26; FIG. 10) up to form-fit whereby the casters of the wheelchair are lifted off of the ground (d; FIG. 10).

The attachment wheel (FIG. 1) has a brakeable and steerable wheel (5) equipped with an one-handed operable steering system (13, FIG. 9) with a brake (44, FIG. 9). This steering system is characterized by two lockable joints (39, 42; FIG. 9) for an angle adjustment and a telescopic mechanism. (40, 41; FIG. 9) for length adjustment. By this features a maximum adaptability of the steering and braking operation to the user is achieved. At its lower half the handlebar stem (14, FIG. 4) is provided with a friction ring (21; FIG. 4) which can be pressed against the outer surface of the steering tube (2) by means of an adjustment clamp (20) thereby forming an adjustable steering resistance. A spring (32) fixed between the handlebar stem (14) and the steering tube (2) provides for a spring-centred straight running of the front wheel. Furthermore, a limitation of the steering angle is obtained by two stops (24) at the steering tube and one at the handlebar stem (14). In addition the front wheel has a straight wheel fork (4) and a steering angle (a; FIG. 10) causing that the wheel contact point (29; FIG. 10) is positioned in driving direction behind the intersection point (30; FIG. 10) of the extended steering axis and the ground.

The features of a spring-centred straight running and a steering resistance (32, 20; FIG. 5), together with the above mentioned positive trail (b; FIG. 10), bring about a stabilized straight running and a steering behaviour familiar to the wheelchair user during two-handed propelling of the unit through the gripping rings of the wheelchair. The front wheel (5; FIG. 1) can directly and comfortably be steered and braked through the one-hand operation (13; FIG. 1) in driving down-hill and along curves. These features enhance the driving safety, reduce the required effort and enable a more efficient movement. The triangle frame with lockable shearing mechanism (17, 18, 19; FIG. 3) and adjustable adaptation shells (FIG. 7, FIG. 8) results in an extremely adaptive frame structure still having a high stiffness. After an one-time setting (18 a; FIG. 3; 33, 35, 34 a; FIG. 7) there is the advantage of performing a fast change between transport mode and functional mode of the attachment wheel and thus of its fast and flexible handling

This embodiment is of high benefit for wheelchair users as it solves essential handling problems and thus effects a mobility benefit not yet known.

REFERENCE LIST

FIG. 1: Perspective General View “Attachment Wheel Adaption with Adaption Ring”

1 frame segment

2 steering tube

3 rotating joint of steering tube

4 wheel fork

5 wheel

6 adaptation ring

7 upper adaptation shell

8 lower adaptation shell

9 tube offset

10 clamping tube offset

11 tensioning mechanism

12 tensioning element with loop

13 one-hand handlebar

14 handlebar stem

15 V brake

17 shearing mechanism

FIG. 2: Plan View “Unit in Packing Size”

1 frame segment

7 upper adaptation shell

13 one-hand handlebar

14 handlebar stem

FIG. 3: Plan View “Unit without Handlebar”

1 frame segment

7 upper adaptation shell

11 tensioning mechanism

12 tensioning element with loop

14 handlebar stem

15 V brake

17 shearing mechanism

18 shearing mechanism guide rail

18 a shearing mechanism fixable lock retainer

19 shearing mechanism arm

26 wheelchair front tube

FIG. 4: Cross-sectional view “Handlebar Stem and Steering Tube”

2 steering tube

14 handlebar stem

16 fork shaft

18 shearing mechanism guide rail

20 adjustment clamp steering resistance

21 friction ring

22 fork shaft clamp

32 return spring

FIG. 5: Exploded View “Handlebar Stem and Steering Tube”

2 steering tube

14 handlebar stem

20 adjustment clamp steering resistance

21 friction ring

22 fork shaft clamping

23 lower bearing shell

24 steering stop

25 slide bearing steering tube

FIG. 6: Cross-sectional View “Adaption Ring”

6 adaptation ring

31 groove for adaptation shells

FIG. 7: Perspective View “Upper Adaption Shell with Joints”plus “Adaption Ring”

1 frame segment

6 adaptation ring

7 upper adaptation shell

28 hook

33 lockable horizontal joint

34 vertical joint

34 a swivel range limitation vertical joint

35 lockable rotating joint

36 connector

FIG. 8: Perspective View “Lower Adaption Shell with Joints”

1 frame segment

8 lower adaptation shell

9 tube offset

10 clamping tube offset

38 rotatable joint connector

FIG. 9: Side View “One-hand Handlebar”

13 one-hand handlebar

14 handlebar stem

39 handlebar height adjustment

40 telescopic tube

41 telescopic tube clamping

42 lockable grip joint

43 grip

44 brake lever

FIG. 10: Diagram “Adaption Procedure”

6 adaptation ring

11 tensioning mechanism

12 tensioning element

13 one-hand handlebar

26 wheelchair front tube

27 casters

29 wheel contact point

30 intersection point of extended steering axis with ground

a steering tube angle

b trail

c tensioning angle

d casters' lift off 

1-15. (canceled)
 16. An apparatus, comprising: an adaptive attachment wheel comprising a wheel and holding elements configured for fastening to different wheelchair frames, wherein the adaptive attachment wheel comprises at least one tensioning element for tensioning the adaptive attachment wheel to a front tube of a wheelchair, thereby, when fastening, lifting off front wheels of the wheelchair off the ground and producing a three-wheeled wheelchair, wherein the adaptive attachment wheel comprises a steering tube and two frame segments which are fastened to the steering tube by respective first ends and to at least three adaptation shells by respective second ends, wherein an opening of each adaptation shell is directed away from the second end of the corresponding frame segment, wherein at least one adaptation ring configured for attachment to the wheelchair front tube is provided which includes a groove adapted to a shape of one of the adaptation shells for inserting the adaptation shell, wherein at least one of the further adaptation shells is configured to be tensioned to the wheelchair front tube by means of the at least one tensioning element attached to one of the two frame segments, wherein a lateral guidance is created at the wheelchair front tube by a shape of the further adaptation shell.
 17. The apparatus of claim 16, wherein at least one of the adaptation shells is fastened to the corresponding frame segment in a swivelling, rotatable or telescopically adjustable configuration.
 18. The apparatus of claim 17, wherein the adaptation shell insertable into the groove of the adaptation ring is configured to be vertically be swivelled and comprises a lockable lower limitation of the swivel range preventing an out-folding of the adaptation shell out of the groove or a peak load to it.
 19. The apparatus of claim 16, wherein an adaptation shell at one end fastened to a frame segment is configured to be telescopically adjusted by means of a lockable tube-in-tube configuration or at least one frame segment comprises a rotary or lengthwise adjustable tube offset.
 20. The apparatus of claim 16, wherein the at least one adaptation ring configured to be attached to the wheelchair is configured as a two-part clamping ring.
 21. The apparatus of claim 16, wherein the adaptation shell insertable into the groove of the adaptation ring comprises a holding device by means of which the adaptation shell is fixable in the groove opposite to the insertion direction.
 22. The apparatus of claim 21, wherein the holding device is a hook, a magnet or a spring steel loop.
 23. The apparatus of claim 16, wherein the two frame segments are connected with the steering tube by at least one rotating joint and adjustable or lockable symmetrically to the steering tube in width by means of a shearing mechanism.
 24. The apparatus of claim 23, wherein the shearing mechanism comprises two arms rotatably fastened to the frame segments, which are centrally brought together on a rail attached to the steering tube and are guided thereon substantially without any play or are lockable in a functional position by means of an adjustable lock retainer.
 25. The apparatus of claim 16, wherein a fork shaft, guided within the steering tube, of a wheel fork is rotatably supported in the steering tube by means of a handlebar stem which is configured to be clamped or a threaded steering set.
 26. The apparatus of claim 25, wherein a rotary resistance is adjustable by a further clamping device with a friction ring.
 27. The apparatus of claim 25, wherein the wheel fork guided within the steering tube and the wheel attached to the wheel fork is configured to be steered or braked by a one-hand handlebar having a tube and a grip at one end, and wherein the one-hand handlebar comprises an adjustment option in height, length or grip angle.
 28. The apparatus of claim 16, wherein the at least one tensioning element has a surface of a surface-preserving material for being placed around a part of the wheelchair, to fasten the apparatus to the wheelchair or a part of the apparatus at one end and tension the adaptation shell to the wheelchair front tube.
 29. The apparatus of claim 28, wherein the surface-preserving material is polypropylene, polyester or nylon.
 30. The apparatus of claim 25, wherein the handlebar stem comprises a steering stop or a clamping at the fork shaft configured to lock the handlebar to the wheel fork, and in connection with a spring, to autonomously return the wheel to a straight-ahead position
 31. The apparatus of claim 20, wherein at least one part of the two-part clamping ring has a groove adapted to the shape of the adaptation shell.
 32. The apparatus of claim 23, wherein the at least one rotating joint comprises at least one ring-shaped metal part fastened to the steering tube.
 33. A three-wheeled wheelchair comprising a wheelchair and the apparatus of claim 16, wherein a positive trial is produced at the attachment wheel when fastened to the wheelchair between the wheel contact point of a wheel installed in the wheel fork and the track point set by the angle of the steering tube so that the running wheel trails the steering system rotational axis in a driving direction. 